There might be food insurance companies. They would have advertisements telling people of a probable military intervention by Xia
and recommend people to buy food insurance in order to be safe.
Regarding your second point: The realization that Xia might attack will probably not come suddenly but slowly. So people will
gradually begin investing in food insurance. It's unlikely that Xia turns from friend to enemy in a matter of days.
The realization that Xia might attack will probably not come suddenly but slowly
Just like 9-11, Dec 7, 1941, the anschluss, mongol invasions...the Hitties and Philistines versus the Israelites, yeah, military ops are always telegraphed.
"Austria was merged into Nazi Germany on 12 March 1938. There had been several years of pressure from Germany and there were many supporters within Austria for the "Heim ins Reich"-movement, both Nazis and non-Nazis." - http://en.wikipedia.org/wiki/Anschluss
Your less specific in the details of your other facts so it's hard to get specific counter-facts on them.
